Epidural analgesia during labour and severe maternal morbidity: population based study

Abstract Objectives To determine the effect of labour epidural on severe maternal morbidity (SMM) and to explore whether this effect might be greater in women with a medical indication for epidural analgesia during labour, or with preterm labour. Design Population based study. Setting All NHS hospitals in Scotland. Participants 567 216 women in labour at 24+0 to 42+6 weeks’ gestation between 1 January 2007 and 31 December 2019, delivering vaginally or through unplanned caesarean section. Main outcome measures The primary outcome was SMM, defined as the presence of ≥1 of 21 conditions used by the US Centers for Disease Control and Prevention (CDC) as criteria for SMM, or a critical care admission, with either occurring at any point from date of delivery to 42 days post partum (described as SMM). Secondary outcomes included a composite of ≥1 of the 21 CDC conditions and critical care admission (SMM plus critical care admission), and respiratory morbidity. Results Of the 567 216 women, 125 024 (22.0%) had epidural analgesia during labour. SMM occurred in 2412 women (4.3 per 1000 births, 95% confidence interval (CI) 4.1 to 4.4). Epidural analgesia was associated with a reduction in SMM (adjusted relative risk 0.65, 95% CI 0.50 to 0.85), SMM plus critical care admission (0.46, 0.29 to 0.73), and respiratory morbidity (0.42, 0.16 to 1.15), although the last of these was underpowered and had wide confidence intervals. Greater risk reductions in SMM were detected among women with a medical indication for epidural analgesia (0.50, 0.34 to 0.72) compared with those with no such indication (0.67, 0.43 to 1.03; P<0.001 for difference). More marked reductions in SMM were seen in women delivering preterm (0.53, 0.37 to 0.76) compared with those delivering at term or post term (1.09, 0.98 to 1.21; P<0.001 for difference). The observed reduced risk of SMM with epidural analgesia was increasingly noticeable as gestational age at birth decreased in the whole cohort, and in women with a medical indication for epidural analgesia. Conclusion Epidural analgesia during labour was associated with a 35% reduction in SMM, and showed a more pronounced effect in women with medical indications for epidural analgesia and with preterm births. Expanding access to epidural analgesia for all women during labour, and particularly for those at greatest risk, could improve maternal health.


eTable
Comparison of adjusted relative risks (RR) and 95% CI for all outcomes comparing labour epidural to no epidural in; preterm and term/post-term births, and in women with and without a medical indication for epidural for cohort restricted to obstetric units (N=541,389).

eTable 5
Observed events for all components of SMM (unimputed data).

in each SMM component per year over the study period of 1 st January 2007 and 31 st December 2019 (unimputed data).
*We redacted any outcome or variable with five or fewer values, or any data which could be used to derive these redacted values.

of adjusted relative risks (RR) and 95% CI for all outcomes comparing labour epidural to no epidural in; preterm and term/post- term births, and in women with and without a medical indication for epidural for cohort restricted to obstetric units (N=541,389).
Derived from likelihood ratio test comparing a model with an interaction between epidural analgesia and the subgroup terms to one without that interaction.†Adjusted for maternal age, ethnicity, Scottish index of multiple deprivation, gestation at birth, parity, induction of labour, year of birth, and smoking in pregnancy.‡Adjusted for maternal height, weight, ethnicity, Scottish index of multiple deprivation, gestation at birth, comorbidity before labour using Bateman index weighted score (restricted to period of 180 days preconception to day before delivery), parity, induction of labour, previous caesarean (before period used for Bateman index), year of birth, smoking in pregnancy. *

eTable 10 Adjusted relative risks (RR) and 95% CI for all outcomes referent to receiving no epidural analgesia (RR = 1) by WHO category of preterm birth: "extremely preterm" (< 28 weeks), "very preterm" (28 to < 32 weeks), and "moderate to late preterm" (≥ 32 to 36+6 weeks), and by category of spontaneous or iatrogenic preterm birth.
Adjusted for maternal height, weight, ethnicity, SIMD, gestation at birth, co-morbidity prior to labour using Bateman index weighted score (restricted to period of 180 days pre-conception to day before delivery), parity, induction of labour, previous caesarean (prior to the time period used for the Bateman index), year of birth, smoking in pregnancy, type of delivery unit.SIMD = Scottish Index of Multiple Deprivation, SMM = Severe Maternal Morbidity, RR = Relative Risk, CI = Confidence Interval

of sepsis compared with incidence of sepsis plus critical care admission over time eFigure 4 Adjusted relative risk for all components of SMM compared with not having an epidural (RR=1)
SMM = Severe Maternal Morbidity.PPH = postpartum haemorrhage.Adult RDS -Adult Respiratory Distress Syndrome.